WO2022027959A1 - One-way homogeneous beam expanding screen and three-dimensional display device - Google Patents

Abstract

An one-way homogeneous beam expanding screen (20) and a three-dimensional display device. The one-way homogeneous beam expanding screen (20) comprises a lenticular grating (22) and at least one linear Fresnel lens (21); the linear Fresnel lens (21) is located between a projection unit (10) and the lenticular grating (22); the linear Fresnel lens (21) comprises a plurality of tooth-shaped structures (211) extending in a second direction (x); the linear Fresnel lens (21) is used for deflecting a light beam emitted by the projection unit (10) and enabling the deflected light beam to be normally incident to the lenticular grating (22); a grating line (221) of the lenticular grating (22) extends along the second direction (x); the lenticular grating (22) is used for uniformly expanding a light beam emitted by the linear Fresnel lens (21) along a first direction (y), wherein the first direction (y) intersects with the second direction (x).

Description

A one-way uniform beam expanding screen and three-dimensional display device

This application claims the priority of the Chinese patent application with application number 202010789272.X filed with the China Patent Office on August 7, 2020, the entire contents of which are incorporated herein by reference.

technical field

The embodiments of the present application relate to a three-dimensional display technology, for example, to a unidirectional uniform beam expanding screen and a three-dimensional display device.

Background technique

In the related art, naked-eye three-dimensional display can be realized by utilizing the principles of holographic projection, lenticular grating, volume three-dimensional, and integrated imaging. As far as the implementation is concerned, the lenticular grating uses the refraction effect of the cylindrical lens to present different pictures to different angles, separates the left and right eye images, and uses parallax to generate a three-dimensional visual effect.

In a three-dimensional display device, vector pixels can be used as image sources, and a lenticular grating can be used to expand the vector pixels in one direction, which can reduce the amount of vector pixels and reduce costs. When the beam expansion angle is relatively small, the uniformity of the beam is relatively consistent. When a large-angle beam expansion is required, the brightness of the edge area will be lower than that of the middle area, resulting in brightness jumps when viewed at different positions in the beam expansion direction, resulting in uneven display.

SUMMARY OF THE INVENTION

The embodiments of the present application provide a unidirectional uniform beam expanding screen and a three-dimensional display device, wherein the unidirectional uniform beam expanding screen can expand the beam emitted by the projection unit in the same direction (ie, the first direction) to have uniform intensity and distribution. The same light cone, the propagation direction and divergence angle along the second direction are unchanged, and the light emitted by the two projection units is uniformly expanded in one direction after the brightness is uniform, so as to avoid the brightness jump of the spliced image, and it is applied to three-dimensional display. The display brightness and uniformity can be improved when the device is installed.

In the first aspect, the embodiment of the present application provides a one-way uniform beam expansion screen, which is set to expand the beams of different exit angles emitted by the projection unit along the first direction into light cones with uniform intensity and the same distribution, and along the second direction. The propagation direction and divergence angle of the direction are unchanged; the one-way uniform beam expanding screen includes a cylindrical grating and at least one linear Fresnel lens;

the linear Fresnel lens is located between the projection unit and the lenticular grating;

The linear Fresnel lens includes a plurality of tooth-like structures extending along the second direction, and the linear Fresnel lens is configured to deflect the light beam emitted by the projection unit, so that the deflected light beam is straight. incident on the lenticular grating;

The grating lines of the lenticular grating extend along the second direction, and the lenticular grating is set to uniformly expand the light beam emitted from the linear Fresnel lens along the first direction;

When the one-way uniform beam expanding screen includes at least two of the linear Fresnel lenses, the linear Fresnel lenses are arranged along the first direction, and the adjacent two linear Fresnel lenses are arranged in the first direction. The light beams received at the seam position and emitted from two adjacent projection units in the first direction pass through the one-way uniform beam expanding screen to form the same distribution;

Wherein, the projection unit corresponds to the linear Fresnel lens one-to-one, the vertical distance between the projection unit and the linear Fresnel lens corresponding to one-to-one is equal to the focal length of the linear Fresnel lens, and the The first direction intersects the second direction.

In a second aspect, an embodiment of the present application further provides a three-dimensional display device, including:

a turntable, which rotates around a central axis of the turntable, the central axis extending along the first direction;

At least one light pole is fixed on the turntable, the light pole includes at least one projection unit, and each of the projection units is arranged to emit light in at least two directions in a plane perpendicular to the first direction, so as to form at least one projection unit. two viewpoints; and

In any one of the above-mentioned one-way uniform light beam expanding screens, the one-way uniform light beam expanding screens are arranged in a one-to-one correspondence with the light poles, and are located on the outgoing light path of the projection unit.

Description of drawings

1 is a schematic structural diagram of a one-way uniform beam expanding screen provided by an embodiment of the present application;

2 is a schematic diagram of an optical path during beam expansion of a one-way uniform beam expanding screen provided by an embodiment of the present application;

3 is a schematic structural diagram of an effective setting area of a projection unit provided by an embodiment of the present application;

4 is a schematic cross-sectional structure diagram of a one-way uniform beam expanding screen provided by an embodiment of the present application;

FIG. 5 and FIG. 6 are respectively schematic top-view structural diagrams of another one-way uniform beam expanding screen provided by the embodiment of the present application;

7 is a schematic cross-sectional structure diagram of another one-way uniform beam expanding screen provided by an embodiment of the present application;

8 is a schematic cross-sectional structure diagram of another one-way uniform beam expanding screen provided by an embodiment of the present application;

9 is a schematic flowchart of a method for preparing a one-way uniform beam expanding screen provided by an embodiment of the present application;

10 is a schematic structural diagram of a three-dimensional display device provided by an embodiment of the present application;

11 is a schematic diagram of a partial structure of a three-dimensional display device provided by an embodiment of the present application;

12 is a schematic partial structure diagram of another three-dimensional display device provided by an embodiment of the present application;

FIG. 13 and FIG. 14 are respectively schematic diagrams for the comparison of distortion correction without a curved mirror and with a curved mirror.

detailed description

The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. It should be noted that the directional words such as "up", "down", "left", and "right" described in the embodiments of the present application are described from the angles shown in the drawings, and should not be construed as implementing the present application. Example limitation. Also in this context, it will also be understood that when an element is referred to as being formed "on" or "under" another element, it can not only be directly formed "on" or "under" the other element, but also Indirectly formed "on" or "under" another element through intervening elements. The terms "first," "second," etc. are used for descriptive purposes only and do not imply any order, quantity, or importance, but are merely used to distinguish the different components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

FIG. 1 shows a schematic structural diagram of a unidirectional uniform beam expanding screen provided by an embodiment of the present application, and FIG. 2 shows a schematic diagram of an optical path during beam expansion of a unidirectional uniform beam expanding screen provided by an embodiment of the present application. . 1 and 2 , the unidirectional beam-spreading screen 20 provided by the present embodiment is set to expand the light beam emitted by the projection unit 10 along the first direction y into a light cone with uniform intensity and the same distribution, along the second direction. The propagation direction and divergence angle of x are unchanged; the one-way uniform beam expanding screen 20 includes a lenticular grating 22 and at least one linear Fresnel lens 21 (only one linear Fresnel lens is schematically shown in FIG. 1 ); linear The Fresnel lens 21 is located between the projection unit 10 and the lenticular grating 22; the linear Fresnel lens 21 includes a plurality of tooth-like structures 211 extending along the second direction x, and the linear Fresnel lens 21 is arranged to connect the projection unit 10 The outgoing light beam is deflected, so that the deflected light beam is normally incident on the lenticular grating 22; the grid lines 221 of the lenticular grating 22 extend along the second direction x, and the lenticular grating 22 is set to emit the linear Fresnel lens 21 The light beams are uniformly expanded along the first direction y; when the unidirectional uniform beam expanding screen 20 includes at least two linear Fresnel lenses 21, the linear Fresnel lenses 21 are arranged along the first direction y, and two adjacent linear The light beams received at the seam position of the Fresnel lens 21 (refer to the dotted line frame in FIG. 2 ) and emitted from two adjacent projection units 10 in the first direction y pass through the unidirectional uniform beam expanding screen to form the same beam. distribution; wherein, the projection unit 10 corresponds to the linear Fresnel lens 21 one-to-one, the vertical distance between the projection unit and the linear Fresnel lens corresponding to the one-to-one is equal to the focal length of the linear Fresnel lens 21, the first direction y and the second Direction x crosses.

Exemplarily, in this embodiment, the first direction y and the second direction x are vertical as an example, where the first direction y may be a vertical direction, and the second direction x may be a horizontal direction. Projection unit 10 may include at least one vector pixel or pico projector. Vector pixel refers to an optical display module composed of a sub-pixel array and an optical module. The sub-pixel array is composed of basic display units of dense display devices (such as Micro-LED arrays). After the sub-pixel array passes through the optical module, each sub-pixel beam is Pointing to different angles in space, only specific sub-pixels can be seen from different directions, that is, the pixels realize vector directivity. The vector pixel meets the following conditions: 1. The point light source has a narrow beam. Relative to the larger display scale, it can be approximately regarded as a light source that emits light (for example, the light source only occupies less than 1/10,000 of the display area), and most of the light beams emitted into the space have the following properties: if the light intensity drops to this point 50% of the maximum light intensity of the light beam is the boundary of the light beam, with the light source as the center, and the minimum space spherical angle that can include all the boundaries is less than 10 degrees. 2. It can support the projection of the above beams in no less than 100 directions that can be distinguished. 3. The above beams can be emitted in at least 2 directions at the same time. 4. The brightness of the above beams can be adjusted at least 16 levels.

Referring to FIG. 2, the projection unit 10 is located at the focal length of the linear Fresnel lens 21, the divergent beam emitted by the projection unit 10 is incident on the linear Fresnel lens 21, and the linear Fresnel mirror 21 only changes the direction of the beam emitted by the projection unit 10 along the first The component propagating in one direction y does not change the component propagating in the second direction x of the light beam emitted from the projection unit 10, and then the linear Fresnel lens 21 deflects the light beam into an approximately parallel light beam that is nearly perpendicular to the lenticular grating 22, and at the same time Without changing the angle of the beam in the second direction x, by designing the shape of each cylinder in the lenticular grating 22, the beam can be uniformly expanded into different divergence angles in the first direction y, and the smaller the focal length of the cylinder, The larger the angle of unidirectional beam expansion. In order to reduce the difficulty of processing, the linear Fresnel lens 21 can be spliced by multiple pieces, and the splicing should be aligned as much as possible to reduce the gap. By designing the linear Fresnel lens 21 , the light 1 emitted by the upper projection unit and the light 2 emitted by the lower projection unit can be almost normally incident on the lenticular grating 22 after passing through the Fresnel lens 21 , and then passing through the lenticular grating 22 at The intensity of the beam expanding in the first direction y is uniform and the distribution is the same, that is, the intensity distribution of light 1 and light 2 are different when they enter the linear Fresnel lens 21, but the intensity distribution is the same after exiting through the unidirectional beam expanding screen. In addition, in the design, the overall thickness of the linear Fresnel lens 21 and the lenticular grating 22 is less than or equal to the focal depth of field of the beam emitted by the projection unit 10, thereby ensuring the clarity of imaging. Optionally, the spot width of one pixel in each projection unit along the first direction on the unidirectional uniform beam expanding screen is d ₁ , the grating constant of the lenticular grating is d ₂ , and d ₁ ≥ 3d ₂ . That is, the light spot of each pixel corresponds to at least three cylinders of the lenticular grating to ensure sufficient resolution during imaging.

Optionally, the number of grating lines of the lenticular grating 22 is greater than or equal to 300 lines per inch, which can be designed according to actual display effects and requirements during specific implementation. When the number of lines of the lenticular grating is small, especially when the width of the lenticular lens is larger than the size of the projection pixel, the imaging beam is unidirectionally expanded after passing through the lenticular grating, and the human eye will see a virtual image enlarged by the projection pixel when viewing. The size is larger than the size of the projection pixel. When the width of the cylinder is smaller than the size of the projection pixel, the projection pixel is divided into multiple parts and projected onto the cylinder grating. At this time, the human eye sees multiple parts of the projection pixel through multiple cylinders. Multiple virtual images will overlap. The larger the number of raster lines, the higher the overlap ratio of multiple partial virtual images, and the closer the seen virtual image is to the projected pixel size.

In the technical solution of this embodiment, by setting a linear Fresnel lens, the linear Fresnel lens deflects the divergent beam emitted by the projection unit into an approximately parallel beam, and then enters the cylindrical grating approximately perpendicularly; The beam emitted by the Fresnel lens expands the viewing angle along the first direction, and the propagation direction and divergence angle along the second direction remain unchanged. Due to the deflection effect of the linear Fresnel lens, the cylindrical grating can achieve uniform beam expansion in the first direction. , when multiple projection units are imaged and spliced, the brightness of the seam can be uniform, and when applied to a three-dimensional display device, the display brightness and uniformity can be improved, and the display effect can be improved.

Optionally, the projection unit 10 is disposed at the focal position of the corresponding linear Fresnel lens 21 . By setting the projection unit 10 at the focal position of the linear Fresnel lens 21, the light incident on the linear Fresnel lens 21 by the projection unit 10 is vertically incident on the lenticular grating 22, and the lenticular grating 22 realizes uniform expansion of all incident light rays. bundle.

Optionally, the projection unit is arranged on the focal plane of the corresponding linear Fresnel lens, and the distance h between the projection unit and the focal point of the linear Fresnel lens satisfies:

where L represents the focal length of the linear Fresnel lens,

Represents the actual beam expansion angle of the one-way uniform beam expansion screen along the first direction, and θ represents the required viewing angle along the first direction.

Since the projection unit has a certain size and expands outward from the focal position, the area that can meet the viewing needs forms the effective incident position area. FIG. 3 is a schematic structural diagram of an effective setting area of a projection unit according to an embodiment of the present application. Referring to Figure 3, L represents the focal length of the linear Fresnel lens, φ represents the actual beam expansion angle of the unidirectional uniform beam expanding screen along the first direction, and θ represents the required viewing angle along the first direction. When the distance h of the focal point of the Fresnel lens satisfies the above formula (1), the sharpness of the image observed by the observer can be guaranteed. Exemplarily, the scattering angle of the one-way uniform beam expanding screen is 60 degrees to meet the viewing needs. When the scattering angle of the one-way uniform beam expanding screen is only 60 degrees, there is only one point in the vertical direction (ie, the first direction y). It is required that the point is located on the optical axis of the unidirectional beam expanding screen. When the scattering angle of the unidirectional beam expanding screen is greater than 60 degrees, for example, the projection unit is 50mm away from the unidirectional beam expanding screen, and the unidirectional beam expanding screen is 50mm away. When the scattering angle of the screen is 70 degrees, the projection unit can be placed in a position within the area of ±4.37mm from the symmetrical position of the optical axis of the unidirectional uniform beam expanding screen in the vertical direction to meet the viewing needs.

For the unidirectional uniform beam expanding screen provided in this embodiment, in order to facilitate installation, the linear Fresnel lens and the lenticular grating are generally designed to be very thin film layers. Schematic diagram of the cross-sectional structure of the uniform beam expanding screen. Referring to FIG. 4 , optionally, the one-way uniform beam expanding screen provided in this embodiment further includes a support mirror 23 located on the side of the lenticular grating 22 away from the projection unit, and the support mirror 23 is configured to support the linear Fresnel lens 21 and Lenticular grating 22 . Optionally, the support mirror 23 may be an equal-thickness lens or a cylindrical concave lens.

4, the support mirror 23 is an equal-thickness lens. At this time, the support mirror 23 only has a supporting function. In other embodiments, the support mirror can also be designed as a cylindrical concave lens. For beam expansion screen projection, there are differences in the optical path of light with different exit angles reaching the one-way uniform beam expansion screen, which will cause aberration after beam expansion through the one-way uniform beam expansion screen. In order to reduce the aberration, optionally, the side of the support mirror 23 close to the projection unit is the first surface, the first surface is a curved surface, the lenticular grating 22 is attached to the first surface of the support mirror 23, and the linear Fresnel lens 21 is attached to the side of the lenticular grating 22 away from the support mirror 23 . Exemplarily, FIG. 5 and FIG. 6 are respectively schematic cross-sectional structural diagrams of another unidirectional uniform light beam expanding screen provided in an embodiment of the present application. Referring to FIG. 5, the first surface can be set as an arc surface, and the projection unit (not shown in FIG. 5) is located at the center of the circle and at the focal point of the linear Fresnel lens, so that the projection unit can emit light in all directions. The distance to the one-way uniform beam expanding screen is the same. By setting the first surface to be a curved surface, it is possible to avoid the distortion and curvature of the unidirectional beam expansion spot caused by the lenticular grating aberration, and to a certain extent reduce the field curvature and distortion caused by the large-angle imaging of the projection unit. Multi-projection unit imaging splicing provides convenience. When the unidirectional beam expanding screen is flat, and the projection unit projects the linear Fresnel lens onto the lenticular grating to expand the beam, the distances between the sub-pixels and the unidirectional beam expanding screen are inconsistent, causing the projection image to be blurred. The sizes are inconsistent, and when the sub-pixels of the projection unit are projected onto the unidirectional beam-expanding screen for imaging, the beam cone axis forming each sub-pixel is not vertically incident on the cylindrical grating of the unidirectional beam-expanding screen, due to the cylindrical mirror image. The reason for the difference is that when the lenticular grating is opened in one direction, the light spot will be distorted, and the final formed one-way beam expanding linear light spot will be bent. When the screen is imaged, the phenomenon of pixel row bending will occur. At this time, if the axial direction of the lenticular grating is bent, the bending will be reduced or eliminated. Therefore, the unidirectional uniform beam expanding screen of the embodiment of the present application is arranged in an arc shape bending. Referring to FIG. 6 , the thickness of the middle area of the support mirror 23 is smaller than the thickness of the areas on both sides. When the projection image source is placed at the midpoint of the focal line of the cylindrical concave lens, the viewing angle of the projection device can be enlarged in one direction, and the specific implementation can be designed according to actual needs. The structure of the support mirror is not limited in the embodiments of the present application.

Referring to FIG. 1 , the linear Fresnel lens 21 and the lenticular grating 22 are integral diaphragms, the toothed structure 211 of the linear Fresnel lens 21 is located on the surface of the integral diaphragm close to the side of the projection unit 10 , and the lenticular grating 22 The surface on the side of the integral diaphragm facing away from the projection unit 10 . Such a design can simplify the structure of the one-way uniform beam expanding screen, reduce the alignment process of the linear Fresnel lens 21 and the lenticular grating 22, reduce the difficulty of preparation and installation, and reduce the cost.

FIG. 7 is a schematic cross-sectional structural diagram of a unidirectional uniform beam expanding screen according to an embodiment of the present application. Referring to FIG. 7 , optionally, the unidirectional uniform beam expanding screen provided in this embodiment includes a first dielectric layer 30 , a second dielectric layer 31 and a third dielectric layer 32 that are stacked in sequence, and the first dielectric layer 30 is located in the second dielectric layer 30 . On the side of the dielectric layer 31 close to the projection unit 10, the refractive indices of the first dielectric layer 30 and the third dielectric layer 32 are both greater than the refractive index of the second dielectric layer 31; the interface between the first dielectric layer 30 and the second dielectric layer 31 The tooth structure 211 of the linear Fresnel lens is provided, the interface between the second dielectric layer 31 and the third dielectric layer 32 is provided with a lenticular grating, and the surface of the third dielectric layer 32 facing away from the second dielectric layer 31 is flat.

Exemplarily, the support mirror 23 may also be included in FIG. 7 . In this case, the support mirror 23 is attached to the side of the first dielectric layer 30 away from the second dielectric layer 31 , or the support mirror 23 is attached to the third dielectric layer 32 away from the second dielectric layer 31 . One side of the second dielectric layer 31 .

The unidirectional uniform beam expanding screen shown in Figure 1 is provided with serrations on both sides. Although it is beneficial to reduce the process cost, it may bring certain difficulties to the installation. Therefore, for the convenience of installation, exemplarily, as shown in Figure 7 Both sides of the one-way uniform beam expanding screen are flat surfaces, and the refractive indices of the first dielectric layer 30, the second dielectric layer 31 and the third dielectric layer 32 are respectively n ₁ , n ₂ and n ₃ , where n ₂ is the smallest, In other embodiments, one side or both sides of the unidirectional beam-spreading screen may also be non-planar, which may be designed according to actual requirements during specific implementation. Fig. 7 also shows a schematic diagram of the optical path transmission of the unidirectional uniform beam expanding screen. According to Snell's theorem, when the parallel beam is at a certain angle from the first medium layer with the refractive index n ₁ on the left side of the unidirectional uniform beam expanding screen When 30 passes through, there will be two refractions, the first time is the left boundary of the vertical one-way uniform beam expanding screen, which enters n ₁ from the air, and the second time is incident from the inclined surface or curved surface (tooth-like structure 211) In the second dielectric layer 31 with a refractive index of n ₂ , an appropriate slope or curved surface is designed according to the incident angle, and the light beam will eventually _enter the third dielectric layer 32 with a refractive index of n ₃ in the horizontal direction. When the second medium layer 31 enters the third medium layer 32 with a refractive index of n ₃ , since the interface between the two media n ₂ and n ₃ is a cylindrical grating, the light beam is unidirectionally turned on after passing through the interface, realizing uniform light unidirectional expansion. bundle. In the plane unidirectional beam expanding screen, the tooth-like structure 211 of the linear Fresnel lens may be composed of at least one of a curved surface or an inclined surface. In other embodiments, the left side surface of the first dielectric layer 30 and the right side surface of the third dielectric layer 32 can also form a curved surface shape when they are attached to the support mirror according to actual needs, and can be designed according to actual needs during specific implementation. .

Exemplarily, the thickness of the second dielectric layer 31 can be very thin, so that the functional surface of the lenticular grating and the functional surface of the linear Fresnel lens can be infinitely approached, and the thicknesses on both sides of the functional surface are suitable for unidirectional uniform beam expansion. The screen performance is not affected, that is, as long as the second dielectric layer 31 between the functional surfaces is kept relatively thin, the thickness of the one-way uniform beam expanding screen is not strictly limited, which can reduce the processing difficulty.

Optionally, the refractive indices of the first dielectric layer and the third dielectric layer are the same. Exemplarily, the first dielectric layer and the third dielectric layer may be formed of the same material, so as to simplify the process difficulty and reduce the fabrication cost of the unidirectional uniform beam expanding screen.

In another embodiment, the unidirectional uniform beam expanding screen can also be designed to be flat on one side. Illustratively, taking the light-emitting surface as a plane as an example, FIG. 8 is a schematic cross-sectional structural diagram of another unidirectional light-homogeneous beam-expanding screen provided in an embodiment of the present application. Referring to FIG. 8 , optionally, the unidirectional beam-spreading screen includes a fourth dielectric layer 40 and a fifth dielectric layer 41 arranged in layers. The fourth dielectric layer 40 is located on the side of the fifth dielectric layer 41 close to the projection unit. The refractive index of the fifth dielectric layer 41 is greater than the refractive index of the fourth dielectric layer 40; the surface of the fourth dielectric layer 40 near the projection unit is provided with a linear Fresnel lens tooth structure 211, the fourth dielectric layer 40 and the fifth The interface of the dielectric layer 41 is provided with a lenticular grating, and the surface of the fifth dielectric layer 41 facing away from the fourth dielectric layer 40 is flat.

Light is incident on the fourth dielectric layer 40 with a refractive index n ₄ from the air, the toothed structure 211 on the fourth dielectric layer 40 is designed as a linear Fresnel lens with a preset focal length, and the projection unit is set on the linear Fresnel lens. At the focal position of , when the light emitted from the focal point passes through the interface between the air and the fourth dielectric layer 40, it can be incident on the fifth dielectric layer 41 with a refractive index of n ₅ in the horizontal direction, n ₅ >n ₄ , the first The interface between the fourth medium layer 40 and the fifth medium layer 41 is designed as a lenticular grating, and after passing through the lenticular grating, the uniform light unidirectional beam expansion of the projection unit can be realized.

In other embodiments, the light incident surface can also be designed to be a plane, and the design idea is similar to that of the above-mentioned embodiment, which will not be described in detail here.

FIG. 9 shows a schematic flowchart of a method for preparing a unidirectional beam-spreading screen provided in an embodiment of the present application. The preparation method provided in this embodiment is used to prepare the unidirectional beam-spreading screen provided in the above-mentioned embodiments, including: Step S110 to Step S130.

Step S110 , forming a linear Fresnel lens, where the linear Fresnel lens includes a plurality of tooth-like structures extending along a certain direction.

Step S120 , forming a lenticular grating, and the grating lines of the lenticular grating extend along a certain direction.

Step S130 , combine the linear Fresnel lens with the lenticular grating, and make the extending direction of the tooth structure and the extending direction of the grating lines of the lenticular grating parallel.

Exemplarily, a linear Fresnel lens and a lenticular grating can be formed on the two surfaces of the one-piece diaphragm, respectively, or two or three kinds of dielectric layers can be used to form the Fresnel lens and the lenticular grating, respectively, and then pasted. Together, the embodiments of the present application do not limit this.

In the technical solution of this embodiment, by forming a linear Fresnel lens and a lenticular grating, the divergent beam emitted by the projection unit is deflected into an approximately parallel beam by the linear Fresnel lens, and then incident on the lenticular grating approximately perpendicularly; The lenticular grating expands the viewing angle of the beam emitted by the linear Fresnel lens along the first direction. Due to the deflection of the linear Fresnel lens, the lenticular grating can achieve uniform beam expansion in the first direction. When multiple projection units are imaging When splicing, the brightness of the seam can be made uniform, and when applied to a three-dimensional display device, the display brightness and uniformity can be improved, and the display effect can be improved.

Optionally, the linear Fresnel lens and the lenticular grating are an integral diaphragm; the toothed structure of the linear Fresnel lens is formed on the surface of one side of the integral diaphragm, and the cylindrical grating is formed in the toothed shape of the integral diaphragm. The surface on the opposite side of the structure. This embodiment can be used to prepare the unidirectional uniform beam expander screen shown in FIG. 1 .

Optionally, the unidirectional uniform beam expanding screen includes a first dielectric layer, a second dielectric layer and a third dielectric layer stacked in sequence; the preparation method includes:

Making linear Fresnel lens molds and lenticular grating molds;

Press the first dielectric layer and the third dielectric layer with a linear Fresnel lens mold and a lenticular grating mold respectively;

The pressed first dielectric layer and the third dielectric layer are bonded by the second dielectric layer. This embodiment can be used to prepare the unidirectional uniform beam expanding screen shown in FIG. 7 .

Optionally, the one-way uniform beam expanding screen includes a fourth dielectric layer and a fifth dielectric layer that are stacked and arranged; the preparation method includes:

forming a lenticular grating on one side of the fifth dielectric layer;

forming a fourth dielectric layer on the lenticular grating;

A linear Fresnel lens is formed on the side of the fourth dielectric layer facing away from the fifth dielectric layer by using the ultraviolet forming technology. This embodiment can be used to prepare the unidirectional uniform beam expanding screen shown in FIG. 8 .

FIG. 10 is a schematic structural diagram of a three-dimensional display device according to an embodiment of the present application. Referring to FIG. 10 , the three-dimensional display device provided in this embodiment includes: a turntable 100 that rotates around a central axis a of the turntable 100 , and the central axis a extends along the first direction y; at least one light pole 200 (shown schematically in FIG. Each light pole 200 is fixed on the turntable 100, and the light pole 200 includes at least one projection unit 10. Lighting in different directions to form at least two viewpoints; and any one of the unidirectional beam-spreading screens 20 provided in the above embodiments, the unidirectional beam-spreading screens 20 are arranged in a one-to-one correspondence with the light poles 200 and are located in the projection unit 10 on the outgoing light path.

The projection unit 10 may include at least one vector pixel or micro-projector. In this embodiment, one light pole 200 corresponds to one unidirectional beam-spreading screen 20. In another embodiment, at least two The light pole 200 corresponds to one unidirectional uniform beam expanding screen 20 , and the embodiment of the present application does not limit the number of the unidirectional uniform beam expanding screen 20 .

In FIG. 10 , the unidirectional uniform light beam expanding screen 20 is arranged on the outside of the light pole 200 is only schematic. In this case, the audience is located outside the three-dimensional display device to observe the three-dimensional image; in another embodiment, it is also possible to The unidirectional beam-spreading screen 20 is arranged on the inner side of the light pole, and the audience is located inside the 3D display device to observe the 3D imaging; Realize the effect of splicing display and large-screen display.

The three-dimensional display device provided by the embodiments of the present application, by setting any one of the unidirectional uniform light beam expanding screens provided by the above embodiments, has the characteristics of uniform display brightness at each viewing angle and good display effect.

FIG. 11 is a schematic diagram of a partial structure of a three-dimensional display device according to an embodiment of the present application. Referring to FIG. 11, optionally, the projection unit 10 includes a first vector pixel 2101, a second vector pixel 2102 and a third vector pixel 2103 arranged along the first direction y; For the linear Fresnel lenses 21 corresponding to the units 10 one-to-one, the center of the second vector pixel 2102 is the same height as the center of the linear Fresnel lens 21 corresponding to the projection unit 10 where the second vector pixel 2102 is located.

The first vector pixel 2101, the second vector pixel 2102 and the third vector pixel 2103 may include red pixels (R), green pixels (G) and blue pixels (B), and the projection unit realizes color display by setting RGB pixels. Exemplarily, in FIG. 11 , the center of the second vector pixel 2102 is the same height as the center of the linear Fresnel lens 21 corresponding to the projection unit 10 where the second vector pixel 2102 is located, and the first vector pixel 2101 and the third vector pixel 2103 are inclined. It is set that the center of the first vector pixel 2101 and the center of the third vector pixel 2103 point to the center of the linear Fresnel lens 21 .

The line connecting the focal point of the linear Fresnel lens 21 and the center of the linear Fresnel lens 21 forms a straight line perpendicular to the first direction y, and the projection unit is located at the focal position of the linear Fresnel lens 21, but the actual projection unit has A certain size, extending outward from the focal position, can meet the viewing needs to form an effective incident position area. The size of this area is related to the scattering angle of the unidirectional beam expanding screen, the distance between the projection unit and the unidirectional beam expanding screen, and the angle required for viewing. See formula (1) above. In this embodiment, it is assumed that the vector pixel itself can meet the distortion requirements for imaging. If the distortion does not meet the requirements, a distortion correction mirror needs to be added in front of each projection unit to reduce imaging distortion.

In the above embodiment, the center of the second vector pixel is the same height as the center of the linear Fresnel lens corresponding to the projection unit where the second vector pixel is located, and the light rays of the first vector pixel and the third vector pixel are obliquely incident on the linear Fresnel lens. , may cause aberration. In order to reduce the aberration caused by the oblique incidence of light, FIG. 12 is a schematic partial structure diagram of another three-dimensional display device provided by the embodiment of the present application. 12, optionally, the projection unit 10 includes a first vector pixel 2101, a second vector pixel 2102, a third vector pixel 2103 and a color combiner 2104, and the color combiner 2104 is set to combine the first vector pixel 2101, the second vector pixel 2101, the second vector pixel 2104, and the The light emitted by the pixel 2102 and the third vector pixel 2103 is emitted from the same position; the one-way uniform beam expanding screen 20 includes a plurality of linear Fresnel lenses 21 corresponding to the projection units 10 one-to-one. The height of the center of the linear Fresnel lens 21 corresponding to the projection unit 10 where the color combining mirror 2104 is located is the same.

The color combination mirror 2104 is made of prisms with different coatings, and two of the three colors of red, green and blue are reflected, and the other is transmitted. The angle of the Neil lens 21 is relatively large, which is beneficial to reduce the aberration during imaging.

In the above-mentioned embodiments, the color projection is formed by including color pixels of different colors in each pixel unit (that is, the projection unit). Under the controllable distribution error, or through software correction, it can be assembled into color, so that the color combiner can be omitted. Optionally, the projection unit includes a vector pixel, that is, the projection unit only includes 2102 of 210 in FIG. 11 or only includes the image 2102 of 210 in 12; the one-way uniform beam expanding screen includes a plurality of linear Fresnel lenses corresponding to the projection units one-to-one, and the center of the pixel unit (ie the center of the projection unit) corresponds to the linear Fresnel lens of the pixel unit. The heights of the centers of the Nell lenses are the same.

Usually, due to the limited resolution of a single vector pixel, the display area is not enough to meet the high-resolution viewing requirements, so there will be a situation where multiple vector pixels are spliced and displayed. In the three-dimensional display device shown in Figure 10, there will be at least two vector pixels (projection units) on a single light pole for splicing display. Since the optical module of vector pixels will produce field curvature and distortion when imaging at a large viewing angle, although the above one-way The curved state of the uniform beam expander screen helps to reduce field curvature and distortion, but there will still be a gap between the images formed by adjacent vector pixels on the one-way beam expander screen during splicing. The method of display software correction achieves seamless splicing, but it will lose more effective display pixels. The reason for the distortion is that the image is deformed due to the inconsistent magnification during imaging, and the lateral magnification of the central area of the lens (ie, the optical module in the vector pixel) imaging is inconsistent with the lateral magnification of the edge. If the central magnification is smaller than the edge magnification Pincushion distortion occurs, and barrel distortion occurs if the central area magnification is greater than the edge magnification. Distortion is caused by lens imaging and is only related to the field of view of the lens. The larger the field of view, the greater the distortion, and the distortion can only be reduced but not eliminated. In order to reduce the gap, optionally, the three-dimensional display device provided in this embodiment further includes a curved mirror, and the curved mirror is located between the light pole and the one-way uniform light beam expanding screen. The curved mirror can be formed for optical glass whose two surfaces have the same center of curvature, thereby reducing the amount of distortion and achieving seamless splicing. Exemplarily, FIG. 13 and FIG. 14 are respectively schematic diagrams showing the comparison of distortion correction without a curved mirror and with a curved mirror, wherein FIG. 13 is before correction (without curved mirror), and FIG. 14 is after uncorrected (with curved mirror) , it can be seen from Figure 13 and Figure 14 that setting the curved mirror can obviously correct the distortion of the splicing area, indicating the display effect. When applied in the three-dimensional display device shown in Figure 10, the vector pixels are arranged vertically on the light pole, and the splicing can be realized only by correcting the horizontal distortion of the vector pixels. Therefore, the above optical glass can only have curvature in the horizontal direction. to meet the needs.

The fixation of the light pole must ensure stability, and the aberration correction can also adopt the digital correction method. By placing the light pole on the test bench, and installing multiple calibrated cameras in all directions outside the test bench, the correction process is automatically completed through feedback. The non-camera area parameters need to be generated by a reasonable difference algorithm. The more cameras, the higher the correction accuracy. Corrections include alignment adjustment, distortion correction, color and brightness correction. After the calibration is qualified, the resulting calibration parameters of each light pole will be stored on its control board.

Optionally, when the designed vertical viewing area is not large, different linear Fresnel lenses can be designed to be used in different areas of the light pole, and the divergence angle of the lenticular grating can be reduced to improve the brightness.

Claims (16)

1. A one-way uniform beam expanding screen (20), which is arranged to expand the beams of different exit angles emitted by the projection unit (10) along a first direction (y) into a light cone with uniform intensity and the same distribution, and along a second direction (y) The propagation direction and divergence angle of the direction (x) are unchanged; the one-way uniform beam expanding screen (20) comprises a cylindrical grating (22) and at least one linear Fresnel lens (21);

   The linear Fresnel lens (21) is located between the projection unit (10) and the cylindrical grating (22);

   The linear Fresnel lens (21) includes a plurality of tooth-like structures (211) extending along the second direction (x), and the linear Fresnel lens (21) is arranged to provide the projection unit (10) ) the outgoing light beam is deflected, so that the deflected light beam is normally incident on the cylindrical grating (22);

   The grating lines (221) of the lenticular grating (22) extend along the second direction (x), and the lenticular grating (22) is arranged to direct the light beam emitted from the linear Fresnel lens (21) along the The first direction (y) is uniformly beam expanded;

   When the unidirectional beam expanding screen (20) includes at least two linear Fresnel lenses (21), the linear Fresnel lenses (21) are along the first direction (y) Arrangement, the light beams received at the seam positions of two adjacent linear Fresnel lenses (21) and emitted from two adjacent projection units (10) along the first direction (y) pass through all the The same distribution is formed after the one-way uniform beam expanding screen (20);

   Wherein, the projection unit (10) is in one-to-one correspondence with the linear Fresnel lens (21), and the vertical distance between the projection unit (10) and the linear Fresnel lens (21) in one-to-one correspondence is equal to For the focal length of the linear Fresnel lens (21), the first direction (y) crosses the second direction (x).
2. The unidirectional uniform beam expanding screen (20) according to claim 1, wherein the projection unit (10) is arranged at the corresponding focal position of the linear Fresnel lens (21).
3. The one-way uniform beam expanding screen (20) according to claim 1, wherein the projection unit (10) is arranged on the focal plane of the corresponding linear Fresnel lens (21), and the projection unit (10) The distance h from the focal point of the linear Fresnel lens (21) satisfies:

   

   Wherein, L represents the focal length of the linear Fresnel lens (21),

   

   represents the actual beam expansion angle of the one-way uniform beam expanding screen (20) along the first direction (y), and θ represents the required viewing angle along the first direction (y).
4. The one-way uniform beam expanding screen (20) according to claim 1, further comprising a support mirror (23) located on the side of the lenticular grating (22) away from the projection unit (10), the support mirror (23) is arranged to support the linear Fresnel lens (21) and the lenticular grating (22).
5. The one-way uniform beam expanding screen (20) according to claim 4, wherein a side of the support mirror (23) close to the projection unit (10) is a first surface, and the first surface is a curved surface , the lenticular grating (22) is attached to the first surface of the supporting mirror (23), and the linear Fresnel lens (21) is attached to the lenticular grating (22) away from the supporting mirror (23) side.
6. The one-way uniform beam expanding screen (20) according to claim 4, wherein the supporting mirror (23) is an equal-thickness lens or a cylindrical concave lens.
7. The unidirectional uniform beam expanding screen (20) according to any one of claims 1 to 6, wherein the linear Fresnel lens (21) and the lenticular grating (22) are an integral diaphragm, so The tooth-like structure (211) of the linear Fresnel lens (21) is located on the surface of the one-piece diaphragm on the side close to the projection unit (10), and the lenticular grating (22) is located on the one-piece film The surface of the sheet facing away from the projection unit (10).
8. The unidirectional uniform light beam expanding screen (20) according to any one of claims 1 to 6, wherein the unidirectional uniform light beam expanding screen (20) comprises a first dielectric layer (30), a second dielectric layer (30) and a second A dielectric layer (31) and a third dielectric layer (32), the first dielectric layer (30) is located on the side of the second dielectric layer (31) close to the projection unit (10), the first dielectric layer The refractive index of the layer (30) and the third medium layer (32) are both greater than the refractive index of the second medium layer (31);

   A toothed structure (211) of the linear Fresnel lens (21) is provided at the interface between the first dielectric layer (30) and the second dielectric layer (31), and the second dielectric layer (31) ) and the third dielectric layer (32) are provided with the lenticular grating (22), and the surface of the third dielectric layer (32) facing away from the second dielectric layer (31) is a plane.
9. The unidirectional uniform beam expanding screen (20) according to claim 8, wherein the first dielectric layer (30) and the third dielectric layer (32) have the same refractive index.
10. The unidirectional uniform light beam expanding screen (20) according to any one of claims 1 to 6, wherein the unidirectional uniform light beam expanding screen (20) comprises a fourth dielectric layer (40) and a fifth dielectric layer (40) arranged in layers. A medium layer (41), the fourth medium layer (40) is located on the side of the fifth medium layer (41) close to the projection unit (10), and the refractive index of the fifth medium layer (41) is greater than the refractive index of the fourth dielectric layer (40);

    The tooth-like structure (211) of the linear Fresnel lens (21) is provided on the surface of the fourth dielectric layer (40) on the side close to the projection unit (10), and the fourth dielectric layer (40) The lenticular grating (22) is provided at the interface with the fifth dielectric layer (41), and the surface of the fifth dielectric layer (41) facing away from the fourth dielectric layer (40) is a plane.
11. The one-way uniform beam expanding screen (20) according to claim 1, wherein one pixel in the projection unit (10) is along a first direction (y) on the one-way uniform beam expanding screen (20). ) of the light spot width is d ₁ , the grating constant of the lenticular grating (22) is d ₂ , and d ₁ ≥ 3d ₂ .
12. A three-dimensional display device, comprising:

    a turntable (100), rotated around a central axis (a) of the turntable (100), the central axis (a) extending along a first direction (y);

    At least one light pole (200) is fixed on the turntable (100), the light pole (200) includes at least one projection unit (10), and each projection unit (10) is arranged to be perpendicular to the Lighting in at least two directions within the plane of the first direction (y) to form at least two viewpoints; and

    The one-way uniform beam expanding screen (20) according to any one of claims 1 to 11, wherein the one-way uniform beam expanding screen (20) is arranged in a one-to-one correspondence with the light pole (200), and is located in the projection on the outgoing light path of the unit (10).
13. The three-dimensional display device according to claim 12, wherein the projection unit (10) comprises a first vector pixel (2101), a second vector pixel (2102) and a first vector pixel (2102) arranged along the first direction (y) Three vector pixels (2103);

    The unidirectional beam-spreading screen (20) includes a plurality of linear Fresnel lenses (21) corresponding to the projection units (10) one-to-one, and the center of the second vector pixel (2102) is the same as that of the projection unit (10). The height of the center of the linear Fresnel lens (21) corresponding to the projection unit (10) where the second vector pixel (2102) is located is the same.
14. The three-dimensional display device according to claim 12, wherein the projection unit (10) comprises a first vector pixel (2101), a second vector pixel (2102), a third vector pixel (2103) and a color combiner (2104) , the color combining mirror (2104) is set to emit light from the first vector pixel (2101), the second vector pixel (2102) and the third vector pixel (2103) from the same position;

    The one-way uniform beam expanding screen (20) includes a plurality of linear Fresnel lenses (21) corresponding to the projection units (10) one-to-one, and the center of the color combination mirror (2104) is aligned with the combination lens (2104). The height of the center of the linear Fresnel lens (21) corresponding to the projection unit (10) where the color mirror (2104) is located is the same.
15. The three-dimensional display device according to claim 12, wherein the projection unit (10) comprises a vector pixel;

    The one-way uniform beam expanding screen (20) includes a plurality of linear Fresnel lenses (21) corresponding to the projection units (10) one-to-one, and the center of the projection unit (10) is connected to the projection unit (10). The heights of the centers of the linear Fresnel lenses (21) corresponding to (10) are the same.
16. The three-dimensional display device according to any one of claims 12 to 15, further comprising a curved mirror, wherein the curved mirror is located between the light pole (200) and the one-way uniform beam expanding screen (20).

Images